When Mets and Yankees fans arrive for the start of the new season, the teams' past and future will be on display side by side—and not just Pedro Martinez and Johan Santana or Andy Pettitte and Joba Chamberlain. At a record-shattering price tag of more than $2.5 billion, twin homes for New York's ball clubs are being readied for their 2009 openings—and in the Bronx in particular, the repercussions are affecting not just the city treasury but the local neighborhood.

At the time of the two teams' ignominious exits last fall, the new stadiums were still little more than skeletons. Since then, decorative arches—granite for the new Yankee Stadium, brick for the Mets' Citi Field—have mostly taken shape, and the seating bowls are in place. Sharp-eyed fans will note the wide gap between the outer and inner structures: As in most modern stadiums (but not relative oldsters like Shea and Yankee), the façades are mere shells around the actual ballparks within, the better to fill the space in between with concession-y goodness.

The similarities, however, stop at the ballpark walls. The Yankees' project has gotten more attention not just because it's displacing more hallowed ground—the biggest controversy for Mets fans has been whether the team will preserve Shea's 1980s-vintage plaster home-run apple—but because it's far vaster in scale. Where Citi Field is going up in a parking lot, the new Yankee Stadium is being erected in the former Macombs Dam and Mullaly parks and, with its accompanying garages, is already transforming its South Bronx environs. It's one reason why the Yanks' costs are so much higher: nearly $1.9 billion, compared to the Mets' comparatively thrifty $850 million. Of that, taxpayers are covering almost half, mostly via tax rebates and other goodies; the latest estimates for total public subsidies, according to figures compiled by the Voice, are $833 million for the Yankees, $449 million for the Mets.

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Amazin' savings: Citi Field, set to open in 2009, will cost $850 million—about half of it covered by taxpayers.

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Blue monster: A new Yankee Stadium rises across the street from the old, in what used to be Macombs Dam Park.

Hidden costs like tax-exempt bonds are to blame for much of the subsidy bloat, but the soaring costs afflicting all city construction come into play here, too. When Mayor Bloomberg first announced the Yankees plan in June 2005, he projected that it would cost $135 million just to replace the parks being demolished for the new stadium (as well as to raze the old stadium and move a water main). By last year, that figure had risen to $195 million, thanks to what the city called "contingency funding," and apparently those contingencies weren't enough: Last week, the city's Economic Development Corporation reported its current projections had reached $190 million for the parks alone, plus another $52 million for "infrastructure."

The signs of all that money being spent are everywhere around the intersection of 161st Street and River Avenue as opening day nears. To the north, in the former Macombs Dam Park, cranes lift into place the final pieces of the new stadium—slightly shorter than the old, but much broader, a salad bowl rather than a tureen. To the southwest, what was until recently a set of ballfields adjacent to the team parking lot is now a sea of earth movers, prepping the land for one of three new parking garages. The decorative frieze—the bit of scrim that architecturally challenged sportswriters usually call the "façade"—is mostly in place atop the stadium's rim, while giant baseballs have been engraved into the underpass beneath the Macombs Dam Bridge approach.

What you won't see are a lot of public parks being built. The largest of the planned replacements, dubbed "Heritage Field," won't be ready for another three years—the current stadium must be torn down first to make way for it. Another, with a track to replace the one now buried beneath the Yankees' infield, has had its opening pushed back to 2011 as well, according to the EDC. Some work has begun on new tennis courts along the Harlem River (about half a mile and one highway overpass away from the old ones), but there's no sign of activity on the vest-pocket kiddie and skate parks promised for the corner of 157th Street and River Avenue. The new Metro-North station to serve the stadium, by contrast, is already taking shape, and scheduled to open next spring.

For local residents already faced with a construction site larger than Ground Zero on their doorstep, the slow pace of the new parks adds insult to injury. Geneva Hester's apartment in an Art Deco building on Jerome Avenue once looked out on a leafy treescape; now she sees a wall that rises straight up only a few feet back from the curb line. Next to it, a garage is going up that will provide free valet parking for the Yanks and 600 of their special guests; workers recently began driving support beams for it, restoring the familiar "PING! PING!" that was the neighborhood's background noise for much of last year. "They work Saturdays, so you don't really get any rest," says Hester. "Even if you close the door, you hear it."

To get her daily exercise, Hester and her neighbors must now rely on a small temporary park below a bridge ramp. To reach the 161st Street shopping strip, meanwhile, requires running a gauntlet of construction fencing and heavy machinery, plus the tangle of traffic that's resulted from multiple street closures. During the rebuild of the original stadium in the mid-'70s, Hester recalls, streets and parks were likewise torn up for two years. How does the current construction compare? "There is no comparison, please. Nothing like this. This is terrible."

One other new revelation from the EDC: The House That Ruth Built is scheduled for demolition in the spring and summer of 2009—in full view of fans filing past en route to the new digs. This promises the kind of drawn-out scene that faced Chicago in 1991, where White Sox fans could watch Comiskey Park's death throes unfolding across the street. (The morbidly curious can visit ballparks.phanfare.com for a slideshow of the carnage in action.)

"It took quite a while to knock Comiskey down," recalls John Aranza, a lifelong Sox fan who sneaked into the old ballpark "maybe a dozen times" during demolition. "I couldn't believe it when that wrecking ball hit. You realize that nothing's sacred. It'll hurt—I'm telling you, it'll hurt."